Polyester film of 2-butene-1, 4-diol and methyl vinyl ether-maleic anhydride copolymer crosslinked with n-vinyl-2-pyrrolidone and process for preparing same



United States Patent PQLYESTER FILM OF 2-BUTENE-1,4-DIOL AND METHYLVINYL 'ETHER-MALEIC COPOLYNIER CROSSLINKED WITH 'N-VINYL-Z- PYRROLIDONEAND PROCESS FOR PREPAR- ING SAME Frederick A. Hesse], Upper Montclair,N.J., and Geraitl Robinson, New York, N.Y., assignors to General Aniline& Film Corporation, New York, N.Y., a corporation of Delaware NoDrawing. Application April 19, 1957 Serial No. 653,757

3 Claims. (Cl. 260--45.4)

properties, is readily prepared by simultaneously disesteri-' fyingmethyl vinyl ether-maleic anhydride copolymer with 2-butene-l,4-di0l toyield a copolymeric polyester which in the presence ofN-vinyl-2-pyrrolidone and the application of heat yields a cross-linkedcopolymeric polyester which may be characterized by the followingformula:

wherein each of the ns represent a chain of 5 to 2,000 monomer units ofpartially esterified methyl vinyl ethermaleic anhydride, and mrepresents an integer ranging from n l to '2 Y which corresponds to amolecular weight of 2,500.11p to as high as 1x10 The cross-linkedcopolymeric polyester having the foregoing structure shows excellentadhesion to various types of surfaces such as wood, glass, metals,paper, cloth, etc. and is unusually adaptable as a rust-preventivecoating for metallic parts. The cross-linked copolymeric polyester isapplied directly from an aqueous solution. The crosslinked copolymericpolyester, after coating and heating the coated surface to a temperatureranging from 130- 210 C. yields coatings or films which show not onlyex- 2,882,257 Patented Apr. 14, 1959 I cellent resistance to water butalso resistance to exposure to ultraviolet light. It also possessesexceptionally good heat resistance and in view of this property isespecially useful in the preparation of bake-type enamel when mixed withpigments. v

In preparing the cross-linked copolymeric polyester of the presentinvention, we prepare an aqueous mixture containing approximately 1 moleof methyl vinyl ethermaleic anhydride copolymer, hereinafter referred tofor sake of simplicity as PVM/MA, 1 mole of 2-butene-1,4- diol and /2mole of N-vinyl-2-pyrrolidone either in the presence or absence of acatalyst and heating the mixture wherein the ns have the .same valuegiven above. Simultaneously, i.e. during diesterification, theN-vinyl-2-pyrrolidone cross-links the copolymeric polyester. The unusualfeature in the preparation of cross-linked copolymeric polyesters isthat the simultaneous diesterification and cross-linking at elevatedtemperatures takes place in an aqueous medium. In view of this featurethe PVM/ MA is preferably employed in aqueous solution wherein theconcentration may range from 10 to 35% PVM/MA. It is to be noted that inthe event an excess of Z-butene- 1,4-diol and/or N-vinyl-2-pyrrolidoneis employed, this has no effect on the diesterification andcross-linking reaction whatsoever with the exception that there may besome unreacted 2-butene-1,4-diol and N-vinyl-Z-pyrrolidone which arewater-soluble and, if the water solution of the cross-linked material isapplied as a coating they nay be either washed out with water orevaporated ofi during the heat treating step.

It is to be further noted that one repeating monomer unit of PVM/MA hasa molecular weight of 156. Therefore for each 156 parts by Weight ofPVM/ MA 1 mole or 88.1 parts by weight of 2-'butene-1,4-diol and /2 moleor 111.13 parts of N-vinyl-Z-pyrrolidona are employed in thesimultaneous diesterification and cross-linking.

Another unusual feature of the present invention is that thecross-linked copolymeric polyester is prepared in situ and applieddirectly from the aqueous medium to all types of coating applications.Heating the cast film between and 210 C. results in a hard, glossy film.

The specific viscosity of the PVM/MA, prior to the making up of anaqueous solution, may range from 0.2 to 3 and the viscosity coefiicient(K) may range from 10 to .200 depending upon the extent ofcopolymerization. The PVM/MA has molecular weights ranging from 500 to250,000. Viscosity measurements are used as an indication of the averagemolecular weight of the copolymers. The viscosity coefiicient, K, isfully described in Modern Plastics 23, No. 3, 157-61, 212, 214, 216, 218(1945), and is calculated as follows:

log 17 rel c of e,u'-azodiisobutyronitrile. stirred, then cast on aglass plate and allowed to dry at where C is the concentration in gramsper 100 cc. or 60- polymer solution in Z-butanone (methylethyl ketone)at 25 C. and 11 rel is the ratio of the viscosity of the solution tothat of pure Z-butanone. The K values are reported as 1000 times thecalculated viscosity co-efiicient in order to avoid the use of decimals.The specific viscosity as employed herein means the relative viscosityminus one at 1 gram of the copolymer in 100 m1. of Z-butanone. Thedirect intrinsic viscosity which corresponds to a K value of 10 to 200ranges from 0.040 to 7.37 respectively.

The number of recurring copolymer units enclosed by ns in the bracketsof both the formulae of the copolymeric polyester B and the cross-linkedcopolymeric polyester A indicate the extent or degree ofcopolymerization and correspond to a chain of to 2000 monomer units. InFormula A m represents an integer ranging from which corresponds to amolecular weight of 2500 to as high as 1X10.

The PVM/ MA copolymers utilized in accordance with the present inventionare available on the open market and are readily prepared byconventional methods well known to those skilled in the polymer andcopolymer art.

In practicing the present invention, 100 parts by weight of a -35%aqueous solution of PVM/ MA having a K value ranging from 10 to 200,preferably between 30 and 100, is mixed in a large glass vessel with 11parts by weight of 2-butene-1,4-diol and 7 parts by weight ofN-vinyl-Z-pyrrolidone with or without a catalytic amount of organicperoxide such as benzoyl peroxide, lauroyl peroxide, tert-butylhydroperoxide, etc. or e,'-azodiisobutyronitrile. The solution is thenstirred and coated on glass,-wood, steel or other surfaces and thecoating or film heated for a few minutes, i.e. 3 to-7 minutes, atapproximately l30-2l0 C. to yield smooth and shiny films.

In addition to the three components, i.e. aqueous PVM/MA,2-butene-l,4-diol and N-vinyl-2-pyrrolidone, with or without thepresence of a catalyst, various pigments, dyes and fillers may be addedand the resulting solution cast and heated to yield excellent films andcoatings.

The invention will be described in greater detail in conjunction withthe following examples. It is to be understood however, that theseexamples are merely illustrative and are not intended to limit the scopeof the invention claimed herein.

Example I To a 500 cc. beaker were added 100 grams of a 20% aqueoussolution of PVM/ MA having a K value of 50, 11 grams of2-butene-l,4-diol and 7 grams of N-vinyl-2- pyrrolidone and a smallamount, approximately 0.9 gram, The solution was well room temperature.The resulting film was then heated at approximately 163 C. for 6 minutesand yielded a very smooth, non-tacky, shiny film with excellent adhesionto glass.

The coated glass plate was then placed in a beaker of water and thewater boiled for 30 minutes without any apparent efiect on the castfilm.

Example II Example I was repeated with the exception that prior tocasting on a glass plate, 40 grams of titanium dioxide powder were mixedthoroughly in the solution until a homogeneous paste results. The pastewas then coated on a glass plate, dried at room temperature and thenheated for 6 minutes at approximately 176 C. The resulting film showedexcellent adhesion. The paste may be employed as a white enamel-typepaint.

Example III 5 grams of a dyestufi? obtained on the open market under thebrand name of Heliogen Green GTA Paste, 20 grams of PVM/MA (as a 20%aqueous solution) having a K value of 100, 2 grams of 2-butene-1,4-diol,1 gram of N-vinyl-2-pyrrolidone and 0.5 gram of a,o:'-aZOdiiSO-butyronitrile. The components were thoroughly mixed. The resultingmixture was so well dispersed that additional dispersing agents normallyused in conjunction with phthalocyanine pastes could be dispensed with.The mixture was padded on cloth made of woven glass fibres and heatedfor 10 minutes at 176 C. The resulting cloth was dyed very evenly andshowed excellent resistance to a No. 1 standard ASTM wash test. Thecrock resistance, both wet and dry, was excellent. This particularmixture gives comparable results on cotton and nylon with the exceptionthat these particular cloths withstand a No. 3 standard ASTM wash test.

In connection with this example, it is to be noted that varying theratios of pigment, dye or other coloring matter makes no difference inthe properties of the resulting film with the possible exception ofimparting lighter or darker shades.

Although theoretically, equimolar ratios of PVM/ MA and2-butene-1,4-diol may be used, it is to be noted, as pointed out above,that wide variations of these ratios may be employed and still yieldsatisfactory cross-linked copolymeric polyesters.

The only factor that is critical, as has been observed in the workingout of the foregoing examples, is the time of heating, and accordingly,variations in heating are very important. 3 minutes at -155 C. appearsto be the minimum. Higher temperatures (up to 210 C.) and longercross-linking time improves the physical properties of the resultingfilm proportionately.

We claim:

1. A dry cross-linked copolymeric polyester film obtained by casting afilm from an aqueous mixture comprising 1 mole of methyl vinylether-maleic anhydride copolymer having a K value from 10 to 200, 1 moleof 2-butene-1,4-dio1 and /2 mole of N-vinyl-2-pyrrolidone and heatingthe cast film to a temperature of 130 to 210 C. until a dry film of thesaid polyester is obtained.

2. The process of preparing a dry cross-linked copolymeric polyesterfilm which comprises mixing in water 1 mole of methyl vinyl ether-maleicanhydride copolymer having a K value of 10 to 200, and 1 mole of2-butene-l,4- diol with /5 mole of N-vinyl-Z-pyrrolidone, followed bycasting a film irom the mixture and heating the resulting film to atemperature ranging from 130 to 210 C. until a dry film of saidpolyester is obtained.

3. The process of preparing a dry cross-linked copolymeric polyesterfilm which comprises mixing in water 1 mole of aqueous methyl vinylether-maleic anhydride copolymer having a K value ranging from 10 to200, 1 mole of 2-butene-1,4-diol, and /2 mole of N-vinyl-2- pyrrolidonein the presence of a catalytic amount of a catalyst selected from thegroup consisting of organic peroxides and a,a'-azodiisobutyronitrile andstirring the mixture to yield an aqueous solution which is then castinto a film and the film heated at 130-210 C. until dry.

No references cited.

1. A DRY CROSS-LINKED COPOLYNERIC POLYESTER FILM OBTAINED BY CASTING AFILM FROM AN AQUEOUS MIXTURE COMPRISING 1 MOLE OF METHYL VINYLETHER-MALEIC ANHYDRIDE COPOLYMER HAVING A K VALUE FROM 10 TO 200, 1 MOLEOF 2-BUTENE-1,4-DIOL AND 1/2 MOLE OF N-VINYL-2-PYRROLIDONE AND HEATINGTHE CAST FILM TO A TEMPERATURE OF 130* TO 210* C. UNTIL A DRY FILM OFTHE SAID POLYESTER IS OBTAINED.